How do I make a rig with one bone?
If I understand your question correctly you just need to be in object mode with your model, then (SH-A) add an "Armature".  Move it into the model's internals somewhere although that's not absolutely necessary.  Press the X-Ray box in it's properties panel under the "Display" tab so you can see it at all times.

Once scaled and positioned, highlite the bone (select it), get into pose mode (CTL-Tab from Object mode).  Highlite it again if it's not already glowing.  Left click on the model to select that first, then with shift held, left click on the bone.  A 'parent' menu will come up.  Select "Bone".  Your mesh model will then be locked to the bone.

Select the bone not the model when back in Object mode, rotate or move it about and your model will follow.